A personal computer central processing unit (CPU) is an assemblage of electronic and solid state semiconductors in an arrangement of components and subcomponents. The functioning of the electronic components within the CPU generates high frequencies which result in the emission of radio frequency (RF) electromagnetic radiation therefrom. In response, the Federal Communications Comission (FCC) has created standards which limit the amount of allowable radio frequency to be emitted from electronic devices. It has been found that any openings in the enclosure surrounding the electronic components of the CPU (or any other electronic device) allow the escape of radio frequency. Therefore, in order to reduce RF emission and to meet FCC guidelines, it is necessary to close and seal any openings as best as practicable.
One source of escaping RF in prior computer enclosures is the expansion slot area generally located in the rear panel of a CPU. An expansion slot allows the interconnection of computer enhancing components to peripheral items. A circuit card may be interconnected by a cable through the expansion slot to other electronic components, such as a keyboard, a printer, or a monitor. To control RF emissions, it is necessary to seal the area around an expansion slot that is being used, as well as to cover and seal an expansion slot that is not being currently used.
One typical approach to containing RF in CPU enclosures has been to place a slot cover over any unused expansion slots and to secure the cover in place with screw(s). However, as a result of mismatches between the edges of the expansion slot and the expansion slot cover, unacceptable levels of RF are sometimes allowed to escape. Thus, there is a need for a method and apparatus to more effectively seal the expansion slots of a CPU to retard the escape of RF.